The present invention relates to a new and improved construction of cabin for an electrostatic powder coating installation which is of the type comprising a filter communicating with the internal space or compartment of the cabin, the side of the filter facing away from the internal compartment of the cabin is exposed to the action of a negative pressure, there also being provided a cleaning device operatively associated with the filter, this cleaning device and the filter being relatively movable.
According to a heretofore known cabin of this type, as disclosed in U.S. Pat. No. 3,902,455, the filter is designed in the form of an endless revolving filter band, the upper run of which forms at one face thereof the floor of the cabin and the other face of which travels over a suction vat or trough connected with an exhaust air-suction blower. The filter band extends over the length of the cabin out of the same and the cleaning device arranged externally of the cabin acts upon the end of the upper run of the filter band which travels out of the cabin. The cleaning device primarily serves for reclaiming the excess coating powder deposited upon the floor of the cabin. Due to its construction the cabin requires a considerable installation area and therefore is especially suitable for use with coating lines having a number of spray stations arranged along the lines, at which there are moved past by means of a conveyor the articles which are to be coated. While in principle it would be possible to reduce the cabin to that size which is suitable for instance for a spray gun which can be manually operated, apart from the spatial requirements, such would be associated with drawbacks of a different nature. In particular, the quantity of coating powder which must be placed in circulation is large in comparison to the quantity used for the actual coating of the articles, so that when using a coating powder of a certain quality, for instance a given color, only for a brief period of time, considerable residual quantities of powder must be tolerated which, when switching to a different quality or type of powder, first must be removed from the cabin and the associated components. Consequently, it should be appreciated that the prior art cabins are really not very suitable when employed for a mode of operation requiring relatively frequent change of the quality or type of the coating powder, rather are more adapted for a mode of operation allowing for the use of the same type or quality of powder over longer time spans.